My engine (2.8) has around 3200 miles on it. I am hoping that the lower intake manifold just needs to be retorqued and it is letting a little oil into the air passages when the intake is under heavy vacuum. This only started happening within the past 300 miles.

I know it can also be caused by leaking intake valve stem seals, but I have new umbrella seals and actually pushed the o-ring seals up in place on the intake side since they never stay in place when installing the retainers. Exhaust side did not have them in place as they all got pushed slightly down during retainer install, and they are inaccessible due to the shield and my exhaust side would not pull oil under engine braking anyways as it remains under pressure.

I also do not think it is leaking through the valve stems because I had that problem before, and every time I started the car up when it had been sitting for a couple hours or more it would puff some blue smoke on start up.

My car is not doing that now, there is never any visible smoke, and it only smells under vacuum.

But what else could it possibly be? It is not a super strong smell like with the old engine where my eyes would water, but it is there for sure. Could it be the PCV? I was under the impression the only thing the PCV does is stop pressure from going INTO the crankcase.

I built my whole engine from new parts (beside the thermostat housing and oil pan) and I know every nut and bolt and spring blah blah on/in the thing. I make great oil pressure, 40psi at idle once warm. Runs great, idles great. Plugs all look clean, my oil level has not changed, it really is burning an undetectable amount of oil, but I cannot stand smelling it anymore (windows down mainly).

I would be looking more for a small leak rather than for buring it in the engine. Think it would difficult for exhaust to enter the windows when moving forward at any speed above a creep. Larry

That was my initial thinking but I am not sure for a few reasons

Why would this oil leak only occur on deceleration?

My car used to burn a ton of oil all the time and it smelled no matter what speed I was going

I do have a side exhaust

I have yet to spot any oil on the engine, I did check when I started to smell oil.

Does it use oil between changes? You'll have to run it some miles to find out I suppose. If not, or if 1 quart, I'd say probably no problem.

Smell could be something like rich fuel mixture in exhaust fumes?

[This message has been edited by 2.5 (edited 07-17-2013).]

No it is definitely oil, and it is very very very little. I am not concerned about the engine, I would just like to know possible causes. Honestly I am more concerned about me having to smell that all the time.

quote Originally posted by zkhennings: But what else could it possibly be? It is not a super strong smell like with the old engine where my eyes would water, but it is there for sure. Could it be the PCV? I was under the impression the only thing the PCV does is stop pressure from going INTO the crankcase.

Part of the job of the PCV system is that it lets faint amounts of oil traverse into the intake itself. If you notice, the "front" side of the engine has a PCV tube that goes directly to the air intake. Over normal operation, residual traces of oil will travel up into the intake. However the idea is that with it going into the intake it would eventually burn off due to mixing in with the combustion mixture (fuel & air). This is normal operation.

With it being an issue where you are only smelling the oil upon deceleration, it could possibly be a PCV issue, where maybe you are smelling more than just residual oil that is not being burned off. When engine braking, you are not applying throttle, so the throttle body butterfly should be near closed and none (or VERY little) of the residual oil would be going through the intake to mix with combustion.

You could simply remove the air intake tube and look at the bottom inside of it to see if there is traces of oil. Clean it up, re-install it, and run it again for a short bit and see if you're seeing more oil. You shouldn't see it within a short period of operation. The idea is that cars with this type setup overtime get residual oil in the intake tube from the PCV simply because not all oil is burned off because it's not pulled through to be combusted.

I think I will Disconnect the pcv line and plug it in the intake quick and run some spare fuel hose from the pcv valve to underneath the car somewhere where I can't smell it, and then engine brake a lot and see if I am still smelling anything. If I am I think I can assume it is not a bad pcv system.

It is definitely not being pulled past the rings, my ring gap was perfect or too small and I would file them to perfect if they were too small. I spaced the rings correctly, and even before the engine was broken in when the rings were not even worn to the cylinder shape yet, there was no oil smell.

I am betting it is the lower intake letting oil in. I will check the torque on the headbolts as well but I really really doubt it changed, I have felpro permatorque Severe Duty headgasketes which require no retorque.

It was the lower intake manifold, Oil was being pulled into some of the runners, and now it has loosened up even more and is leaking oil above the timing cover. Ill have to pop that off and re-gasket everything. I will also cut some grooves into the block and the LIM where the RTV goes above the timing cover and distributor. Why does this manifold leak? And what can I do to keep it from loosening? Do you think now that the engine has been fully broken in and the heads have decided where they like to be that if I just put some threadlocker on the bolts I won't have this problem again?